1. Field of the Invention
The present invention relates to a filter, and more specifically to a filter including a plurality of LC parallel resonators.
2. Description of the Related Art
As an invention related to a filter according to related art, for example, there is a multilayer band pass filter described in International Publication No. 2007/119356. FIG. 19 is an exploded perspective view of a multilayer band pass filter 500 described in International Publication No. 2007/119356.
The multilayer band pass filter 500 includes a laminate 502, and LC parallel resonators 504, 506, 508, 510, and 512. The laminate 502 is formed by laminating a plurality of insulator layers together. Each of the LC parallel resonators 504, 506, 508, 510, and 512 includes conductor layers and via hole conductors, and is in the form of a loop when seen in plan view from a direction substantially orthogonal to the laminating direction. The loop planes of the LC parallel resonators 504, 506, 508, 510, and 512 overlap one another.
In the multilayer band pass filter 500, the loop planes of the LC parallel resonators 504, 506, 508, 510, and 512 are slightly shifted from one another. Consequently, the degree of coupling between the LC parallel resonators 504, 506, 508, 510, and 512 is lowered, thereby making it possible to narrow the pass band of the multilayer band pass filter 500. As a result, the multilayer band pass filter 500 having a desired transmission characteristic is obtained.
Filters that can provide a desired transmission characteristic as described above are being desired.